1. Field of the Invention
This invention relates to an apparatus for monitoring the photographic processing liquid for use in a camera processor. The photographic processing liquid such as the developing liquid if exposed to air at an elevated temperature, will be oxidized, and the amount of oxides in the liquid will increase with time. Also, in the course of developing strip of photographic film halogen ions will result in the developing liquid. These oxides and halogen ions in the liquid will suppress the developing effect, accordingly lowering the developing capability of the liquid. In this connection it is necessary that the developing liquid is monitored in terms of the length of timer after the renewal of the liquid and the amount of photographic film already processed to determine when the liquid is to be renewed for keeping the developing capability of the liquid at a constant level.
2. Description of the Prior Art
A conventional apparatus for monitoring the photographic processing liquid operates so that it determines the pH value of the developing liquid and automatically renews the liquid so as to maintain the pH of the total liquid at a given constant value. The apparatus of this type is suitable for use in a large-sized camera processor for commercial use. The apparatus performs the monitoring of the developing liquid automatically, and therefore it is convenient. The structure of the apparatus, however, is much complicated, and accordingly the apparatus is expensive. Another conventional monitoring apparatus uses a counter to determine the length of the processing photographic film so as to determine when the developing liquid is renewed. The indirect indication of the renewal time on the counter is somewhat difficult to discern. Each of the conventional monitoring apparatus mentioned above monitors the processing liquid in terms of the amount of the processed photographic film. This monitoring is not proper to the infrequent use of the camera processor, as for instance in an office. Because the camera processor installed in the office is infrequently used, the effective period of time of the developing liquid expires before the amount of the photographic film which has been actually processed within the "effective period of time" reaches the amount of the photographic film which would have been processed if the apparatus had been continuously used for the "effective period of time". In this connection as long as the monitoring is performed in terms of the amount of the photographic film processed, it is likely that the liquid which has lost the developing capability is used.